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Colors and sight

  1. Feb 28, 2008 #1
    Everyone is obviously familiar with the spectrum of color we see as roygbiv. But is there some kind of color or sight that we don't know of. Could there be some different image that we couldn't even fathom. If someone is born blind they obviously know black but how could they even begin to try to understand red or blue or any color for that fact.
     
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  3. Feb 29, 2008 #2

    jim mcnamara

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    Color blind people report "seeing" colors their eyes cannot create - during really vivid dreams for example. I guess you could take that to mean something stimulated the visual cortex to produce the color sensation.

    There are color receptors - cone cells - in the retina. The area in the brain where the signals are processed into images, the visual cortex, is where "sight" lives, so to speak. This area of the brain is plastic.

    Baseler, H.A., Bewer, A.A., Sharpe, L.T., Morland, A.B., Jagle, H. and Wandell, B.A. (2002). Reorganization of human cortical maps caused by inherited photoreceptor abnormalities. Nat. Neurosci. 5, 364-370

    'rod monochromats' are fully color blind, and have no cone cells. These are the cells that perceive color.

    What Baseler et al.[5] discovered was that the area of cortex that receives information only from the central part of the retina -- the foveola -- in normal color vision is activated by the rod system in rod monochromats. Because there are no rods in the foveola in either these or normal individuals, this central activation developed from a reorganization of the primary visual cortex. This was due to their altered visual experience.

    In other words the brain learned to deal with a new non-color data input set using areas of the brain that were not really meant for "black and white" processing.

    As to understanding color when you have not seen it, this sounds more like Philosophy maybe. How do we know that what our brain tells us is out there is real?

    And only a percentage of people who are blind perceive no light whatsoever. Many blind people can see colors, they just cannot see well enough to get around well visually.
     
  4. Feb 29, 2008 #3

    Andy Resnick

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    Colorimetry is more interesting than first appears. The visualization of pure spectral colors is fairly straightforward (with the possible exception of the blue-violet-red path not obeying the physical spectrum).

    Other colors, like brown or pastel hues, are not so obvious. "Brown" is not a color in the physical sense: it does not have a spot on the CIE chart. The detailed understanding of our visual cortex- from the rods and cones through the optic nerves- is not available yet.

    Some animals are sensitive to portions of the spectrum outside what we can see: bees can see ultraviolet, snakes can see infrared.
     
  5. Feb 29, 2008 #4
    But wouldn't a bee who sees ultraviolet really just be seeing a color that we see all the time? Just that the mind assigns a color too it. Kind of like when we view astronomical pictures in different wavelengths and how they fix a color to it so we can view it.
     
  6. Feb 29, 2008 #5

    Andy Resnick

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    We can't see ultraviolet. At least, I can't.

    I guess I don't understand what you are asking.
     
  7. Feb 29, 2008 #6

    Evo

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  8. Feb 29, 2008 #7
  9. Feb 29, 2008 #8

    Moonbear

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    As asked, the original question is unanswerable, since it requires us to speculate about "some different image that we couldn't even fathom." If we can't fathom it, it's hard to discuss.

    Given that, the discussion on visual perception introduced by Jim and Andy is quite interesting, so we can keep the thread open on that topic rather than the precise question asked in the OP.
     
  10. Feb 29, 2008 #9
    I'm not really trying to get much out of the original question. Basically is it possible that there is some kind of image that we can't see? More asking about the possibility of it.
     
  11. Feb 29, 2008 #10

    NoTime

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    Machinery can show us images we can't see.
     
  12. Mar 1, 2008 #11
    I guess come to think about my questions can't really be answered anyway. It would kind of be like asking if there is life after death. If there is some kind of other image or color that we can't see then how could we prove it? When I refer to this other image or color I'm not referring to the electromagnetic spectrum, but more in physiological terms.
     
  13. Mar 1, 2008 #12

    Q_Goest

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    What Andy said about various animals having the capacity for perceiving wavelengths of light outside those that humans can perceive is the part of the answer. Birds in particular have been an area of study to understand this affect.

    There is the metaphysical aspect of how do our brains create this phenomena we call color, but there is a much more practical aspect as well. I think we have to base responses on the assumption that there is an experience an animal such as a bird is having, and not dismiss the metaphysical aspect. However, I don’t think there’s any need to go any deeper into the metaphysical aspect of color than this. Short story: yes there are different experiences animals can have which are presumed to correspond to an experience of color that humans don’t have. So we have to assume they are experiencing something (ie: a color) which humans can’t see.

    Bees for example are trichromats that have 3 cones for color perception, just like people, but their cones are not identical. At least one of them is able to react to light in the ultraviolet spectrum.

    Birds are more interesting as they are much more intelligent than bees and also they are tetrachromats with 4 different cones for color vision. I’ve seen some false image photos of what a bird might see when compared to what humans see, and these images show features that are very real but totally invisible to us. Can’t seem to find any on the net right now.

    Both bees and birds can resolve different reflected light than humans can, so I think it is reasonable to say they have different experiences of that color than humans do. However, the perception of color is an intrinsic part of a given species, so as far as we know, you and I will never be able to perceive different colors than the ones we experience presently. We’d need to experience them as a different species, in which case we couldn’t compare those experiences to what we experience today as humans.
     
  14. Mar 1, 2008 #13

    NoTime

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    There is a lot of work in color perception around.
    I think Polaroid did some of the original work.

    One thing to consider is that Yellow and Brown are electromagnetically the same.
    We distinguish the two colors based on the background brightness.
     
  15. Mar 1, 2008 #14

    russ_watters

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    The question was already answered quite correctly: seeing different wavelengths such as the IR or UV would allow us to see things we currently can't. It isn't just about assigning colors to objects - we'd see some objects fundamentally differently. We'd see air! (technically, we can see it now, but the sky is near completely opaque to some wavelengths).
     
  16. Mar 2, 2008 #15
    Well the fact that flowers colours have been set up to appeal to a bees or other pollinators sense of colour perception not ours, which in the case of bees is skewed towards the ultraviolet is very interesting, and it's not too hard to show what a bee might see. Given that we think that a bee cannot see the other red end of the spectrum. Thus if you filter out all reds and introduce an idea of what ultraviolet would look like if we could see it. Then you get a sort of idea of a bees eye view.

    Here's a rather neat series of images of how we'd imagine a bee would see colour, of course we cannot really know what a bee sees, but our guesses are interesting.

    http://www.pbase.com/kds315/image/80136802/original.jpg

    And here's an idea of what a flower looks like in UV.

    http://taos-telecommunity.org/EPOW/EPOW-Archive/archive_2004/EPOW-041004.htm
     
  17. Mar 2, 2008 #16

    Vid

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    LSD can induce temoporary synaesthesia which is why I believe we could potentially understand a lot more about the brain if scientists were allowed to study psychedelics in their research.
     
  18. Mar 4, 2008 #17

    Andy Resnick

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    From what I see around here, some people are indeed regularly using psychadelics. :)
     
  19. Mar 4, 2008 #18

    jim mcnamara

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    FWIW-
    Canids, like wolves, see up 1200nm - infared. Humans with normal vision can see 400nm to 700nm. Amphibians, like frogs, primarily see motion, because their underlying translation of images responds mostly to changes in "pixels". So in this sense, motion could be extended as a basic property of vision, like color for humans.

    Another area of perception of light is circadian cycles, and photoperiod. While it is not color, photoperiod does have effects on human behavior and as well as many other members of the Chordata. Circadian rhythms are very well documented in humans as well.

    Lunar cycles and tidal cycles also have profound effects on some species.

    So, how you define perception of light can be very broad indeed.
     
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